1. Field
Example embodiments in general relate to a combination ceiling tile integrated with a light emitting diode (LED) fixture, a LED fixture and a ceiling tile configured to receive one ore more LED strips thereon.
2. Description of the Related Art
Lighting systems are responsible for about 35 percent of the electricity costs in a typical commercial building and 10 percent in industrial settings. Conventional fluorescent lamps such as T8 lamps with electronic ballast are used for new fixtures and retrofits in typical settings such as commercial office buildings, schools, and in industrial lighting. The inside of a fluorescent lamp includes electrodes and a gas containing argon and mercury vapor. A stream of electrons flows through the ionized gas from one electrode to the other, to collide with the mercury atoms and excite them. As the mercury atoms move from the excited state back to the unexcited state, the atoms give off ultraviolet photons. The photons hit the phosphor coating on the inside of the fluorescent tube, and this phosphor creates visible light photons.
Fluorescent bulbs are fabricated in several sizes, examples including 2′, 3′, 4′ and 8′ lengths for straight tubes, and 8″ and 12″ circular shapes. The straight tubes have a cycle life of about 20,000 hours (7-10 years, on average), whereas the circular bulbs are rated at an average life of about 12,000 hours. The straight tubes are often bundled in sets of 2-4 lamps within a housing known as a troffer that is integrated within a ceiling tile space, typically taking up the space of one or two standard 2′×2′ ceiling tile spaces or a single 2′×4′ standard ceiling tile space.
However, the use of fluorescent lighting poses several problems. For example, fluorescent lamps require a ballast to stabilize the lamp and to provide the initial striking voltage required to start the arc discharge. Additionally, because the arc is quite long relative to higher-pressure discharge lamps, the amount of light emitted per unit is low, so fluorescent lamps are typically large. Further, some find the color spectrum produced by fluorescent lighting harsh and displeasing.
One common problem is that the mercury inside a fluorescent tube tends to migrate to one end of the tube, leading to only one end of the lamp producing most of the light. Moreover, the disposal of phosphor and the small amounts of mercury in the tubes poses an environmental issue.
Fluorescent lamps typically operate best around room temperature (for example, about 68 degrees Fahrenheit or 20 degrees Celsius). At much lower or higher temperatures, lamp efficiency decreases; at low temperatures (below freezing) standard fluorescent lamps may not start. Special fluorescent lamps are therefore needed for reliable service outdoors in cold weather.
Another common problem with fluorescent lighting is that fluorescent lamps do not give out a steady light. Instead, and particularly toward the end of tube life, the lamps often flicker (fluctuate in intensity) at a rate that depends on the frequency of the driving voltage. While this is not easily discemable by the human eye, it can cause a strobe effect. This annoying “disco strobe” effect is particularly common with fluorescents at the end of tube life. The strobe effect poses a safety hazard in a workshop for example, where something spinning at just the right speed may appear stationary if illuminated solely by a fluorescent lamp.
LEDs are becoming widely used in many consumer lighting applications. In consumer applications, one or more LED dies (or chips) are mounted within a LED package or on an LED module or strip, which may make up part of a lighting fixture which includes one or more power supplies to power the LEDs. The module or strip of a fixture includes a packaging material with metal leads (to the LED dies from outside circuits), a protective housing for the LED dies, a heat sink, or a combination of leads, housing and heat sink. Various implementations of LED fixtures including one or more LED modules, arrays or strips of LEDs are becoming available in the marketplace to fill a wide range of applications, such as area lighting, indoor lighting, backlighting for consumer electronics, etc. LEDs may offer improved light efficiency, a longer lifetime, lower energy consumption, no environmental disposal issues and reduced maintenance costs, as compared to light sources such as T8 fluorescent lamps.